1. Field of the Invention
The invention generally relates to hair grooming appliances. More particularly, the invention relates to heatable hair brushes.
2. Description of the Prior Art
Hair brushes are well known in the prior art and comprise a generally elongated handle to which is attached an axially aligned hairwinding portion formed as a base having a plurality of outwardly extending bristles. Hair brushes are available as either heatable or non-heatable units, as well as units having either a rotatable or non-rotatable hairwinding portion. Heatable hair brushes are often provided with self-contained means for heating the hairwinding portions, although the heating means is conventional and forms no part of this invention.
Non-heatable hair brushes are used merely for brushing hair or for styling it with the assistance of an auxiliary heat source such as a blow dryer. Heatable hair brushes are used for brushing as well as styling by setting or curling hair and do not require auxiliary heat sources. The bristle patterns on non-heatable hair brushes vary considerably. However, on all known heatable hair brushes the hairwinding portion is generally cylindrical and formed as a base or barrel with the bristles being longitudinally spaced along and radially extending from the barrel and annularly symmetrical about the barrel axis. Example of such prior art heatable hair brushes are shown in U.S. Pat. Nos. 4,486,915 (Stewart et al), No. 4,329,567 (Kunz et al) and No. 4,593,708 (Goeller et al), all assigned to the assignee hereof.
Heatable hair brushes may be manufactured with the bristles being either integrally formed with the barrel (as shown in the aforementioned Stewart et al and Kunz et al patents) or made of dissimilar material and attached to the barrel (as shown in the aforementioned Goeller et al patent). Integral-bristle hair brushes are generally injection molded from a suitable plastic material and, because of the symmetrical bristle arrangement, require use of a multi-part mold. This complexity obviously increases the manufacturing cost. The cost is also relatively high in non-integral-bristle hair brushes because of the parts and labor required to provide the annularly symmetrical bristle arrangement.
In addition to the increased cost of heatable hair brushes having annularly symmetrically arranged bristles, there is a limitation associated with the use of such brushes. As is well understood by those skilled in the art, such brushes are suitable for styling hair by applying heat to the hair as it is manipulated by the brush. In the use of such brushes to straighten hair or to relax curls or waves set in hair, the brush is moved through the hair without being rotated about the barrel axis as it would be to curl the hair. The bristles hold the hair under tension while the heat of the barrel and bristles break the set so that as the hair cools and sets under tension it will become straighter. The application of a predetermined amount of heat is necessary for this operation, although excessive heat will burn the hair. In annularly symmetrical type brushes, whether the bristles are integrally formed or not, the periodic longitudinal spacing of the bristles causes the hair to gather into a clump between adjacent longitudinally spaced bristles. This necessarily results in the hair touching the barrel getting more heat than the hair further away from the barrel, thus creating a risk of burning some of the hair before enough heat is applied to relax the outer layers. It is apparent that prior art brushes are optimized for styling or curling rather than straightening the hair.
It is accordingly an object of this invention to produce a hair brush which may be relatively inexpensively manufactured. It is a further object of this invention to produce a hair brush capable of being injection molded in a two-part mold.
It is also an object of this invention to produce a hair brush capable of being used for either curling or straightening hair as desired. It is yet another object of this invention to produce a hair brush suitable for straightening hair while minimizing the risk of burning the hair before it is sufficiently straightened.